For decades, restorative dentists and dental product manufacturers have attempted to develop a soft liner for dentures and prosthetic devices addressing the various short term and long term clinical challenges presented by partially and fully edentulous patients. Examples of long term uses of soft denture liners may be indicated where the patient has undercuts caused by severe alveolar ridge resorption; anatomical voids requiring obturators; anatomical growths such as palatal tori; and, knife edge alveolar ridges. Examples of short term uses of soft denture liners include overdentures supported by implants or teeth; post-surgical prosthodontic situations that require interim lining while both soft and hard tissue heal; and, gasket like connectors and liners over and around existing teeth.
Various types of soft denture liners exist in the art which are intended for short term or long term service. Soft denture liners are known in the art which are laboratory-processed and intended as long term liners, such as include Molloplast-B.TM. (Buffalo (Dental). Also known in the art are chairside-processed soft liners intended for short term service. These include Lynal.TM. (L.D. Caulk/Dentsply) and Visco-Gel.TM. (Ash/Dentsply). Until the methods of the present invention were developed, no soft denture liner was known that was chairside or laboratory-processed and intended for short, intermediate and long term clinical use.
In addition, prior art liners have different problems associated with their clinical applications. In particular, silicon soft liner materials must be "glued" onto the hard acrylic surface with an adhesive bonding agent, and often this bonding agent contains a methyl methacrylate monomer. These self-curing adhesives leach into the soft material and harden it.
Moreover, adhesives harden and crack at the "seam," or junction where the soft material is glued on to the hard acrylic. Lactic acid, alcohol, and/or medication accelerate this separation. At this point, bacteria, fungus, odor, debris, and stain penetrate the soft liners. This natural absorption degrades the soft liners creating a hardening, peeling, as well as chemically and physiologically unstable condition.
In addition, the repair process of other existing materials is difficult since the base material either flakes off when trimmed, or it cannot be re-molded with standard dental tools. Also, to "glue" small sections of liner onto thin acrylic edges is difficult or impossible as the liners break off under the constant pressure which occurs in the oral cavity.
There are various products which use heat or light to cure resins of various formulation onto prosthetic devices. Almost all of these formulations require a bonding agent which runs into the same problems as mentioned above. Many of these finished liners absorb liquids accelerating their deterioration.
Another category of liners which are temporary in nature are known as "tissue conditioners". These gels or stick-on resins last only weeks or a few months before they peel-off. They usually are soft due to high porosity, and thus they absorb liquids which ultimately breakdown the materials. The absorbency allows bacteria and odor buildup in the mouth creating an undesirable situation.
Hence, prior to the development of the present invention, a need existed for clinical techniques using a non-methyl methacrylate soft liner material capable of remaining soft during intermediate to long term service and is chairside or laboratory compatible.